1. Field of the Invention
The present invention relates to a heat-curable resin composition suited to use within an optical semiconductor device, and relates more specifically to a resin composition that comprises an isocyanuric acid derivative containing an epoxy group and a silicone resin containing an epoxy group, and yields a cured product that is resistant to discoloration caused by the light and heat from an optical semiconductor, as well as an optical semiconductor device in which the cured product is used for protection or encapsulation.
2. Description of the Prior Art
Conventionally, polyphthalamide resins (PPA) are used for encapsulating optical semiconductor elements such as light emitting diodes (LED). However, recent developments have resulted in a marked increase in the output and a significant shortening of the wavelength of these optical semiconductor devices. Accordingly, optical semiconductor devices such as photocouplers that are capable of emitting or receiving light at a high output level, and particularly devices having semiconductor element-encapsulating resins or cases that use a conventional PPA resin, tend to suffer marked light degradation upon prolonged use of the device, and are prone to various problems including color irregularity of the emitted light, detachment of the encapsulating resin, and deterioration in the mechanical strength.
The use of isocyanuric acid derivative epoxy resins has been proposed as a method of addressing the problems described above (see Patent Documents 1 to 4). However, these resins are still unsatisfactory in terms of resolving the problem of discoloration.
[Patent Document 1] JP 2002-302533 A
[Patent Document 2] US 2003/0132701 A1
[Patent Document 3] JP 2005-306952 A
[Patent Document 4] WO 2007/015427
[Patent Document 5] JP 2004-99751 A